Method
1. Clean the prawns by removing its shell and deveining it.
2. Pat the pieces dry using a paper towel.
3. Mix salt, turmeric powder and red chilly powder. Apply over the prawns and toss it so that every piece gets coated well.
4. Let it rest and marinate for at least half an hour.
5. Deep fry the prawns over medium heat. We want the pieces to be golden brown without getting burnt.
6. Drain and remove the pieces.
7. Coarsely crush the mustard seeds, cumin seeds and fenugreek seeds using a motor and pestle. Add it to the same oil.
8. Add the ginger, garlic, curry leaves and green chilies. Shallow fry this on low heat.
9. Once the mixture gets cooked, add the vinegar. If you want more gravy, add some water.
10. Switch off. Add the fried prawns and toss well.
11. Let this pickle rest for about 2 days for the flavors to blend together.

Hi, you have to deep fry the shrimp in order to get a long shelf life. If stored in the refrigerator, the pickle stays good for upto 6 months. In room temperature it will be good for upto a month. If you plan to store for a long period, you need to add enough oil so that the pickle is submerged in oil.